I can enter the site ok in FF, and choose New Posts, New Replies or My Posts (from my profile), but it won't go any further when I try to open any particular post - just get "waiting for FPF" and the spinning circle.
I get no error messages.
I've cleared cookies and cache several times.

In Opera and Google Chrome, the site is perfectly OK.
On a Win7 / IE laptop the site works correctly.

I've tried FF in Safe Mode, have reset it, and even removed, rebooted and reinstalled it, all to no avail.
Everything else works correctly, so although I'm not convinced it's a FF issue I've looked at Mozilla Help, but found no answer.

Proxy settings are the same in all 3 browsers.
I've also rebooted my router.